Just back from South Africa where a couple of a the big supermarket chains have now equipped their stores with LCD price tags on the shelf edges instead of good old printed paper tags. Not sure whether they are updated wirelessly at a distance or by a person running around the store with a handheld programmer. I thought it was a bit of an overengineered solution but they must have found some benefit to warrant rolling it out. This plastic display and/or e-ink solutions I would have thought a better technology, not least because they would be easier to read than the blue-on-transreflective-LCD. You're also looking at tens of thousands of units per large supermarket, which could provide economies of scale quite early on.